Fuel cells may be employed as a power supply for an increasing number of large-scale applications, such as materials handling (e.g. forklifts), transportation (e.g. electric and hybrid vehicles) and off-grid power supply (e.g. for emergency power supply or telecommunications). Smaller fuel cells are now being developed for portable consumer applications, such as notebook computers, cellular telephones, personal digital assistants (PDAs), and the like.
In a typical conventional fuel cell (e.g. a fuel cell stack), fuel travels to the anode of a membrane electrode assembly (MEA) via bipolar plates having flow channels. Aside from fuel distribution, bipolar plates also function to separate unit fuel cells. The use of bipolar plates may increase the space occupied by the fuel cell stack and system. In order to ensure that there is electrical contact between bipolar plates and MEAs and to prevent fuel and oxidant from leaking out, conventional fuel cell stacks must be held together with compressive force. Various components may be used to hold conventional fuel cell stacks together. Conventional fuel cell stacks may therefore require many parts and assembly may be quite complex.
Fuel cells may also be connected in edge-collected configurations, such as planar configurations. In some edge-collected fuel cell designs, current is collected from the edges of individual unit cells and travels in the plane of the fuel cells.
Some edge-collected or planar fuel cell systems do not employ compressive force in order to maintain good contact between the fuel cell layer and various other components of the fuel cell system. In such fuel cell systems, components may be assembled and held in contact by other means.
Edge-collected fuel cells may be used to power portable consumer applications, such as notebook computers, cellular telephones, personal digital assistants (PDAs), and the like. Such applications often have little space available for a fuel cell system.